#!/bin/bash

#
# Bottles of Beer song in Bash
#
# A way-overcomplicated implementation of the bottles of beer song in bash.
# Optional argument:
#
#  *  `--careless` - Generate the "happen to fall" version
#
# NOTE:  This is an altered version of a "99 bottles of beer" song
# Bash script by Bill Brown.  The intent of the altered version is
# to show the style, so the above text is preserved from [the
# original][99b].
#
#   [99b]: http://99-bottles-of-beer.net/language-bash-1831.html
#

pred() {
    #
    # Get predecessor to a number $1
    #
    local numeral=$1    # number in word form
    case $numeral in
        *nine)      echo ${numeral%nine}eight;;
        *eight)     echo ${numeral%eight}seven;;
        *seven)     echo ${numeral%seven}six;;
        *six)       echo ${numeral%six}five;;
        *five)      echo ${numeral%five}four;;
        *four)      echo ${numeral%four}three;;
        *three)     echo ${numeral%three}two;;
        *two)       echo ${numeral%two}one;;
        one)        echo zero;;
        *-one)      echo ${numeral%-one};;
        *one)       echo ${numeral%one};;
        ten)        echo nine;;
        eleven)     echo ten;;
        twelve)     echo eleven;;
        *teen)      teenpred $numeral;;
        *ty)        tenspred $numeral;;
        zero)       echo "";  #to terminate
    esac
}

teenpred() {
    #
    # Get predecessor of a teen $1
    #
    local numeral=$1    # number in word form
    case $numeral in
        thirteen)   echo twelve;;
        *)          echo $(crunchprefix $(pred $(uncrunchprefix ${numeral%teen})))teen;;
    esac
}

tenspred() {
    #
    # Get predecessor of a multiple of ten $1
    #
    local numeral=$1    # number in word form
    case $numeral in
        twenty)     echo nineteen;;
        *) echo $(crunchprefix --tens $(pred $(uncrunchprefix ${numeral%ty})))ty-nine;;
    esac
}

crunchprefix() {
    #
    # Crunch number prefix $1 to its conventional form
    #
    # ...such as `three` --> `thir`
    #
    # option `--tens` - multiples of ten are a bit different
    #
    local numeral       # number in word form
    local tensop        # 'true' if --tens option is active
    [ $1 = --tens ] && { tensop=true; shift; }
    numeral=$1
    case $numeral in
        two)    [ -n "$tensop" ] && echo twen || echo $numeral;;
        three)  echo thir;;
        four)   [ -n "$tensop" ] && echo 'for' || echo $numeral;;
        five)   echo fif;;
        eight)  [ -n "$tensop" ] && echo eigh || echo $numeral;;
        *)      echo $numeral;;
    esac
}

uncrunchprefix() {
    #
    # Reverse crunchprefix $1
    #
    local prefix=$1     # numeral crunch-prefix
    case $prefix in
        twen)   echo two;;
        thir)   echo three;;
        'for')  echo four;;
        fif)    echo five;;
        eigh)   echo eight;;
        *)      echo $prefix;;
    esac
}

grammar() {
    #
    # Apply peculiarities of English grammar to text on stdin
    #
    local oneBottle=false   # 'true' if this line affects the following line
    local line              # every line
    while read line; do
        line="${line/one more bottles/one more bottle}"
        case "$line" in
            *"one of those bottles"*)   line="$([ $oneBottle = true ] &&
                                        echo ${line/one of those bottles/that lone bottle} ||
                                        echo $line )"
                                        ;;
            *"one down"*)               line="$([ $oneBottle = true ] &&
                                        echo ${line/one down/it down} ||
                                        echo $line )"
                                        ;;
            *bottles*)                  oneBottle=false;;
            *bottle*)                   oneBottle=true;;
        esac
        #Some say the twenties should have no hyphen
        line="${line/twenty-/twenty }"
        echo $line
    done
}

capitalize() {
    #
    # Fix capitalization of each line on stdin
    #
    local line      # every line
    while read line; do
        echo -n ${line:0:1} | tr '[:lower:]' '[:upper:]'
        echo ${line#?}
    done
}

punctuate() {
    #
    # Add punctuation to each line on stdin
    #
    local line      # every line
    while read line; do
        case "${line}" in
            [Ii]f*)     echo ${line},;;
            '')         echo;;
            *)          echo ${line}.;;
        esac
    done
}

verse() {
    #
    # Write one verse with number $1
    #
    local nb=$1     # numeral
    echo $nb bottles of beer on the wall
    echo $nb bottles of beer
    if [ $nb = zero ]; then
        echo Go to the store and buy some more
        nb=ninety-nine
    else
        echo $breakLine
        nb=$(pred $nb)
    fi
    echo $nb bottles of beer on the wall
}

poeticize() {
    #
    # Make text on stdin nice
    #
    local first     # first word of a line
    local rest      # remainder of a line
    local syl       # number of syllables in the first word
    while read first rest; do
        case "$rest" in
            *beer*)
                first=${first/zero/no}
                syl=$(syllables ${first% *})
                case $syl in  #improve meter
                    1|2)    echo $first 'more' $rest;;
                    *)      echo $first $rest;;
                esac
                ;;
            *)  echo $first $rest
        esac
    done
}

syllables() {
    #
    # Estimate number of syllables in word $1
    #
    local word=$1   # word (numeral) to do the estimation on
    local n=1
    case $word in
        eleven)     n=2;; #sounds better if not considered 3
        *teen)      n=2;;
        *ty)        n=2;;
        *-*)        n=3;; #don't care about more than 3
    esac
    case $word in
        *seven*)    let $((n = n+1));;
    esac
    echo $n
}

main() {
    local breakLine             # bottle-break (or not) line
    local standardBreakLine     # ^^ standard variant
    local wastefulBreakLine     # ^^ wasteful (bottle breaks) variant
    local nb            # beginning number
    standardBreakLine="Take one down and pass it around"
    wastefulBreakLine="If one of those bottles should happen to fall"
    breakLine=$(
        [ "$1" = --careless ] \
         && echo $wastefulBreakLine \
         || echo $standardBreakLine
    )
    nb=ninety-nine
    while [ -n "$nb" ]; do
        verse $nb
        echo
        nb=$(pred $nb)
    done | poeticize | grammar | punctuate | capitalize
}

main "$@"